scope:

This International Standard specifies the substitution method for determining the insertion loss of ducted silencers. It sets out requirements for determining - the insertion loss, in frequency bands of silencers with and without air flow; - the sound power level, in frequency bands, of the flow noise generated by silencers; - the total pressure loss of silencers with air flow. The measurement procedures are intended for laboratory measurements on silencers but may also be used for in situ measurements on silencers if the requirements of this International Standard can be met. This International Standard applies to silencers for ventilating and air-conditioning systems, which are usually connected to ducts or splitter absorbers mounted in ducts. Other duct elements, such as bends or T-connectors, may also be tested using this International Standard. This International Standard does not apply to reactive silencers used for motor vehicles.